title: Stimulants of Toll-like receptor (TLR)-2 and TLR-4 are abundant in certain minimally-processed vegetables.
abstract: Stimulants of the innate immune receptors Toll-like receptor (TLR)-2 and TLR4 have been shown to promote insulin resistance and atherosclerosis in animal models of these diseases. As minimally processed vegetables (MPV) can contain a relatively large bacterial load compared to other foodstuffs, we aimed to quantify the abundance of stimulants of TLR2 and TLR4 in MPV using a transfection-based bioassay calibrated with Escherichia coli LPS and the synthetic lipopeptide Pam(3)CSK(4). Of 5 classes of MPV and 3 classes of related vegetable products considered to be likely to contain a high microbial load, diced onion and bean sprouts contained the highest levels of stimulants of TLR2 (up to 18.5 μg Pam(3)CSK(4)-equivalents per g) and TLR4 (up to 11.4 μg LPS-equivalents per g). By contrast, the majority of fresh whole vegetables examined reproducibly contained minimal or undetectable levels of TLR2- or TLR4-stimulants. The accumulation of TLR-stimulants in MPVs correlated well with growth of enterobacterial spoilage organisms. In conclusion, the modern trend towards eating minimally processed vegetables rather than whole foods is likely to be associated with increased oral exposure to stimulants of TLR2 and TLR4.
authors.affiliation: Department of Cardiovascular Sciences, Glenfield General Hospital, University of Leicester, Leicester LE3 9QP, UK. ce55@le.ac.uk
authors.forename: Clett
authors.initials: C
authors.lastname: Erridge
mesh_terms: D004926:Escherichia coli / Q000187:drug effects / Q000276:immunology; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D057809:HEK293 Cells; D006801:Humans; D007333:Insulin Resistance / Q000276:immunology; D008070:Lipopolysaccharides / Q000494:pharmacology; D010936:Plant Extracts / Q000276:immunology / Q000494:pharmacology*; D015398:Signal Transduction; D051195:Toll-Like Receptor 2 / Q000187:drug effects* / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000187:drug effects* / Q000378:metabolism; D014162:Transfection; D014675:Vegetables / Q000737:chemistry* / Q000382:microbiology
chemical_list: D008070:Lipopolysaccharides; D010936:Plant Extracts; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4